President Thomas Jefferson receives a subpoena to testify in the treason trial of his former vice president, Aaron Burr, on this day in 1807. In the subpoena, Burr asked Jefferson to produce documents that might exonerate him.

Burr had already been politically and socially disgraced by killing former Treasury secretary and Revolutionary-era hero Alexander Hamilton in a duel in 1804. After killing Hamilton, Burr, still Jefferson’s vice president, went into hiding to avoid prosecution for murder. (The charges were later dropped.) Burr then concocted a seditious plan to enlist the help of Britain and Spain to create a separate nation in the southwestern reaches of the American continent, including parts of Mexico, over which Burr would rule. The outrageous plan failed miserably when one of Burr’s co-conspirators, General James Wilkinson, betrayed Burr and alerted Jefferson to the plot. Burr was hunted down and arrested in 1806 and indicted for treason.

Jefferson expressed in his personal papers that he felt no love or loyalty to Burr despite their former political relationship. Burr had run a close and contentious election against the republican Jefferson in the 1800 campaign. After the election resulted in a tie, the vote went to the House of Representatives. Only after Alexander Hamilton reluctantly lobbied for Jefferson did the House select Jefferson for the presidency instead of Burr. This was only one of the many grievances Burr held against Hamilton that led to the fatal duel.

Jefferson refused to appear in Burr’s defense and released only a few of the documents Burr had requested, invoking his presidential right to protect the public interest. If Jefferson’s intent was to help get Burr convicted, his refusal to supply documentation backfired. In the end, Supreme Court Chief Justice John Marshall found Burr not guilty by lack of evidence.